1. Field of the Invention
The present invention relates to an LED lighting apparatus for lighting a plurality of LEDs.
2. Description of Related Art
An example of the LED lighting apparatus for lighting a plurality of LEDs (light emitting diodes) is disclosed in Japanese Unexamined Patent Application Publication No. 2004-327152 (Patent Document 1).
FIG. 1 is a schematic view illustrating the LED lighting apparatus disclosed in Patent Document 1. This apparatus is a non-insulated LED lighting apparatus having a triac serving as a dimmer. In FIG. 1, the triac TR1 phase-controls an AC input voltage. The phase-controlled voltage from the triac TR1 is passed through a rectifier 107, is detected by a controller 114, and is converted by an RMS detector 105 into a target voltage Vref for an LED current to be supplied to an LED 102.
A comparator 109 finds an error between the target voltage Vref and a detected voltage representing an LED current detected by a detection resistor R1. In such a way as to minimize the error from the comparator 109, a PWM circuit 113 conducts PWM control on a switching element FET1.
In this way, the LED lighting apparatus according to the related art employs the triac TR1 to phase-control an effective input voltage and change an LED current, thereby dimming the LED 102.